The present invention concerns the detection of exposed nuclear DNA. More especially, this invention concerns a method to diagnose cancer by determining the presence or absence of exposed nuclear DNA in cells and to monitor the progress of cancer therapy. The present invention also concerns a kit useful for detecting the presence or absence of exposed nuclear DNA.
Reverse transformation is a reaction in which malignant cells are restored to a normal phenotype in response to particular agonists as in the CHO-K1 cell treated with cyclic AMP derivatives. See Hsie, A. W., and T. T. Puck, Proc. Natl. Acad. Sci. USA (1971), volume 68, pages 358-361. It involves a succession of complex metabolic changes varying from early alterations in calcium ion dynamics occurring during the first minute, to changes in membrane and cytoskeletal structures, and protein syntheses and phosphorylations which extend over a period of more than 48 hours. See Bunn, P. A., D. G. Dienhart, D. Chan, T. T. Puck, M. Tagawa, P. B. Jewett, and E. Braunschweiger, Proc. Natl. Acad. Sci. USA (1990), volume 87, 2162-2166; Porter, K. R., T. T. Puck, A. W. Hsie, and D. Kelley, Cell (1974), volume 2, pages 145-158; Puck, T. T., The Molecular Biology of the Mammalian Genetic Apparatus (1977), pages 171-180; Gabrielson, E. G., C. Scoggin, and T. T. Puck, Exp. Cell Res. (1982), volume 142, pages 63-68; Chan, D., A. Goate, and T. T. Puck, Proc. Natl. Acad. Sci. USA (1989), volume 86, pages 2747-2751; and Miranti, C., and T. T. Puck, Somat Cell Molec. Genet. (1990), volume 16, pages 67-78. Ultimately, the pathway must result in specific changes in nuclear gene activity which restore specific differentiation and growth control properties to the affected cells. Through modified techniques developed for demonstrating sensitivity to hydrolysis of nuclear DNA, it has previously been demonstrated that an increase in DNA sensitivity to hydrolysis which affects specific nuclear genes and involves a substantial fraction of the genome occurs in the course of Reverse Transformation See Kerem, B., R. Goitein, G. Diamond, H. Cedar, and M. Marcus, Cell (1984), volume 38, pages 493-499; Hutchison, N., and H. Weintraub, Cell (1985), volume 43, pages 471-482; Schonberg, S., D. Patterson, and T. T. Puck, Exp. Cell Res. (1983), volume 145, pages 57-62; and Ashall, F., N. Sullivan, and T. T. Puck, Proc. Natl. Acad. Sci. USA (1988), volume 85, pages 3908-3912. This large-scale increase in DNase I sensitivity of chromatin following treatment of cells with specific reverse transformation agents is now termed genome exposure It has been demonstrated that cytoskeletal integrity is required for this reaction and that the degree of increased exposure achieved in reverse transformation resembles that in normal cells. See Ashall, F., and T. T. Puck, Proc. Natl. Acad. Sci. USA (1984), volume 81, pages 5145-5149.
The present invention demonstrates that cancer cells lack DNase I-sensitive regions of the genome which in normal cells are preferentially localized at the nuclear periphery. Thus, the present invention may be utilized in the diagnosis of cancer (e.g., in pap smears) and to monitor the progress of cancer therapy. Since the present invention demonstrates that normal cells have a DNase I-sensitive region localized at the nuclear periphery, the present invention might be utilized to investigate pathological conditions which result in a compromise in nuclear function (e.g., genetic diseases, neurodegenerative diseases).